Splitting phonons: Building a platform for linear mechanical quantum computing.

Linear optical quantum computing provides a desirable approach to quantum computing, with only a short list of required computational elements. The similarity between photons and phonons points to the interesting potential for linear mechanical quantum computing using phonons in place of photons. Although single-phonon sources and detectors have been demonstrated, a phononic beam splitter element remains an outstanding requirement. Here we demonstrate such an element, using two superconducting qubits to fully characterize a beam splitter with single phonons. We further use the beam splitter to demonstrate two-phonon interference, a requirement for two-qubit gates in linear computing. This advances a new solid-state system for implementing linear quantum computing, further providing straightforward conversion between itinerant phonons and superconducting qubits.

Injury-associated levator ani muscle and anal sphincter ooedema following vaginal birth: a secondary analysis of the EMRLD study.

OBJECTIVE: To determine whether all three components of the levator ani muscle (pubovisceral [= pubococcygeal], puborectal and iliococcygeal) and the external anal sphincter are equally affected by oedema associated with muscle injury after vaginal birth. DESIGN: Observational cross-sectional study. SETTING: Michigan Medicine, University of Michigan. POPULATION: Primiparous women classified as high risk for levator ani muscle injury during childbirth. METHOD: MRI scans obtained 6-8 weeks postpartum were analysed. Muscle oedema was assessed on axial and coronal fluid-sensitive magnetic resonance (MRI) scans. Presence of oedema was separately determined in each levator ani muscle component and in the external anal sphincter for all subjects. Descriptive statistics and correlation with obstetric variables were obtained. MAIN OUTCOME MEASURES: Oedema score on fluid-sensitive MRI scans. RESULTS: Of the 78 women included in this cohort, 51.3% (n = 40/78) showed muscle oedema in the pubovisceral (one bilateral avulsion excluded), 5.1% (n = 4/78) in the puborectal and 5.1% (n = 4/78) in the iliococcygeal muscle. No subject showed definite oedema on external anal sphincter. Incidence of oedema on the pubovisceral muscle was seven times higher than on any of the other analysed muscles (all paired comparisons, P < 0.001). CONCLUSIONS: Even in the absence of muscle tearing, the pubovisceral muscle shows by far the highest incidence of injury, establishing that levator components are not equally affected by childbirth. External anal sphincter did not show oedema-even in women with sphincter laceration- suggesting a different injury mechanism. Developing a databased map of injured areas helps understand injury mechanisms that can guide us in honing research on treatment and prevention. TWEETABLE ABSTRACT: Injury-associated levator ani muscle and anal sphincter oedema mapping on MRI reveals vulnerable muscle components after childbirth.

OPTN/SRTR 2019 Annual Data Report: Kidney.

Despite the ongoing severe shortage of available kidney grafts relative to candidates in need, data from 2019 reveal some promising trends. After remaining relatively stagnant for many years, the number of kidney transplants has increased each year since 2015, reaching the highest annual count to date of 24,273 in 2019. The number of patients waiting for a kidney transplant in the United States was relatively stable, despite an increase in the number of new candidates added in 2019 and a decrease in patients removed from the waiting list owing to death or deteriorating medical condition. However, these encouraging trends are tempered by ongoing challenges. Nationwide, only a quarter of waitlisted patients receive a deceased-donor kidney transplant within 5 years, and this proportion varies dramatically by donation service area, from 15.5% to 67.8%. The non-utilization (discard) rate of recovered organs remains at 20.1%, despite adramatic decline in the discard of organs from hepatitis C-positive donors. Non-utilization rates remain particularly high for Kidney Donor Profile Index ≥85% kidneys and kidneys from which a biopsy specimen was obtained. While the number of living-donor transplants increased again in 2019, only a small proportion of the waiting list receives living-donor transplants each year, and racial disparities in living-donor transplant access persist. As both graft and patient survival continue to improve incrementally, the total number of living kidney transplant recipients with a functioning graft is anticipated to exceed 250,000 in the next 1-2 years. Over the past decade, the total number of pediatric kidney transplants performed has remained stable. Despite numerous efforts, living donor kidney transplant remains low among pediatric recipients with continued racial disparities among recipients. Congenital anomalies of the kidney and urinary tract remain the leading cause of kidney disease. While most deceased donor recipients receive a kidney from a donor with KDPI less than 35%, the majority of pediatric recipients had four or more HLA mismatches. Graft survival continues to improve with superior outcomes for living donor recipients.

Fourteen Years of Archaeological and Heritage Research in the Iringa Region, Tanzania.

The Iringa Region is famous among archaeologists for the Acheulean site of Isimila, and among historians as the stronghold where Chief Mkwawa led the Hehe resistance against German colonial forces. However, our research reveals that Iringa has a rich archaeological record that spans the period from the Stone Age into the recent past. This article summarizes the results of 14 years of research by our team, the Iringa Region Archaeological Project (IRAP). Since 2006, IRAP members have recorded 67 sites, and this only scratches the surface of the archaeological potential in the area. These sites, some of which were recorded in conjunction with local participants, have archaeological component characteristic of the Early, Middle, and Later Stone Age, the Iron Age, and the recent past. We consider the archaeological and historical value of Iringa to be high and hope that this work inspires future research, tourism, and conservation efforts in the area.

La région d'Iringa en Tanzanie est. reconnue par les archéologues pour le site acheuléen d'Isimila et parmi les historiens comme le fief où le chef Mkwawa a dirigé la résistance du Hehe contre les forces coloniales allemandes. Cependant, nos recherches révèlent qu'Iringa possède de riches archives archéologiques allant de l'âge de pierre au passé récent. Cet article résume les résultats de quatorze années de recherche de notre équipe, le projet archéologique de la région d'Iringa (PARI). Depuis 2006, les membres du PARI ont enregistré 67 sites, ce qui ne fait qu'effleurer la surface du potentiel archéologique de la région. Les sites identifiés présentent des éléments archéologiques caractéristiques de l'âge de pierre précoce, moyen et postérieur, de l'âge du fer, et du passé historique. En outre, un certain nombre de sites culturels importants ont été enregistrés en collaboration avec des participants locaux. Nous considérons que la valeur archéologique et historique d'Iringa est. élevée et espérons que ces travaux inspireront la recherche, le tourisme et la conservation dans cette région importante.

Fully Automated Segmentation of Globes for Volume Quantification in CT Images of Orbits using Deep Learning.

BACKGROUND AND PURPOSE: Fast and accurate quantification of globe volumes in the event of an ocular trauma can provide clinicians with valuable diagnostic information. In this work, an automated workflow using a deep learning-based convolutional neural network is proposed for prediction of globe contours and their subsequent volume quantification in CT images of the orbits. MATERIALS AND METHODS: An automated workflow using a deep learning -based convolutional neural network is proposed for prediction of globe contours in CT images of the orbits. The network, 2D Modified Residual UNET (MRes-UNET2D), was trained on axial CT images from 80 subjects with no imaging or clinical findings of globe injuries. The predicted globe contours and volume estimates were compared with manual annotations by experienced observers on 2 different test cohorts. RESULTS: On the first test cohort (n = 18), the average Dice, precision, and recall scores were 0.95, 96%, and 95%, respectively. The average 95% Hausdorff distance was only 1.5 mm, with a 5.3% error in globe volume estimates. No statistically significant differences (P = .72) were observed in the median globe volume estimates from our model and the ground truth. On the second test cohort (n = 9) in which a neuroradiologist and 2 residents independently marked the globe contours, MRes-UNET2D (Dice = 0.95) approached human interobserver variability (Dice = 0.94). We also demonstrated the utility of inter-globe volume difference as a quantitative marker for trauma in 3 subjects with known globe injuries. CONCLUSIONS: We showed that with fast prediction times, we can reliably detect and quantify globe volumes in CT images of the orbits across a variety of acquisition parameters.

Antidepressant medication exposure and 5-HT1A autoreceptor binding in major depressive disorder.

OBJECTIVE: We have previously reported higher brain serotonin 1A (5-HT1A ) autoreceptor binding in antidepressant-naïve patients with Major Depressive Disorder (MDD) compared with healthy volunteers, and a decrease in binding in MDD after selective serotonin reuptake inhibitor (SSRI) treatment. This SSRI effect is also present in rodents administered SSRIs chronically. We therefore sought to determine the duration of antidepressant medication effects on 5-HT1A receptor binding after medication discontinuation. METHODS: Positron emission tomography (PET) imaging with the 5-HT1A receptor radioligand [11 C]WAY-100635 was performed in 66 individuals with current DSM-IV MDD to examine relationships between 5-HT1A binding and time since most recent antidepressant treatment. All subjects were medication-free for at least 2 weeks prior to scanning. Thirty-two additional MDD comparison subjects were antidepressant naïve. RESULTS: No differences in [11 C]WAY-100635 binding were observed between antidepressant naïve and antidepressant exposed MDD groups in 13 a priori cortical and subcortical regions of interest, including raphe autoreceptors, assessed simultaneously in linear mixed effects models. Furthermore, [11 C]WAY-100635 binding did not correlate with time off antidepressants in the antidepressant exposed patients considering these ROIs. The same results were observed when effects of treatment discontinuation of any psychotropic medication used to treat their depression was examined. CONCLUSION: These results indicate that any antidepressant-associated downregulation of 5-HT1A autoreceptor binding reverses within 2 weeks of medication discontinuation. Since this effect is hypothesized to mediate the antidepressant action of SSRIs, and perhaps other antidepressants, it suggests that patients who need ongoing treatment may relapse rapidly when medication is discontinued. Moreover, 2 weeks appears to be a sufficiently long washout of antidepressant medications for a reliable measure of illness-related binding levels.

Revisiting The Spectral and Timing Properties of NGC 4151.

NGC 4151 is the brightest Seyfert 1 nucleus in X-rays. It was the first object to show short time delays in the Fe K band, which were attributed to relativistic reverberation, providing a new tool for probing regions at the black hole scale. Here, we report the results of a large XMM-Newton campaign in 2015 to study these short delays further. Analyzing high quality data that span time scales between hours and decades, we find that neutral and ionized absorption contribute significantly to the spectral shape. Accounting for their effects, we find no evidence for a relativistic reflection component, contrary to early work. Energy-dependent lags are significantly measured in the new data, but with an energy profile that does not resemble a broad iron line, in contrast to the old data. The complex lag-energy spectra, along with the lack of strong evidence for a relativistic spectral component, suggest that the energy-dependent lags are produced by absorption effects. The long term spectral variations provide new details on the variability of the narrow Fe Kα line. We find that its variations are correlated with, and delayed with respect to, the primary X-ray continuum. We measure a delay of τ = 3.3 - 0.7 + 1.8 days, implying an origin in the inner broad line region (BLR). The delay is half the Hß line delay, suggesting a geometry that differs slightly from the optical BLR.

Excavations at Mlambalasi Rockshelter: a Terminal Pleistocene to Recent Iron Age Record in Southern Tanzania.

The Mlambalasi rockshelter in the Iringa Region of southern Tanzania has rich artifactual deposits spanning the Later Stone Age (LSA), Iron Age, and historic periods. Middle Stone Age (MSA) artifacts are also present on the slope in front of the rockshelter. Extensive, systematic excavations in 2006 and 2010 by members of the Iringa Region Archaeological Project (IRAP) illustrate a complex picture of repeated occupations and reuse of the rockshelter during an important time in human history. Direct dates on Achatina shell and ostrich eggshell (OES) beads suggest that the earliest occupation levels excavated at Mlambalasi, which are associated with human burials, are terminal Pleistocene in age. This is exceptional given the rarity of archaeological sites, particularly those with human remains and other preserved organic material, from subtropical Africa between 200,000 and 10,000 years before present. This paper reports on the excavations to date and analysis of artifactual finds from the site. The emerging picture is one of varied, ephemeral use over millennia as diverse human groups were repeatedly attracted to this fixed feature on the landscape.

L'abri sous roche Mlambalasi dans la région d'Iringa au sud de la Tanzanie est riche en artéfacts du Paléolithique supérieur jusqu'à l'âge du fer et la période historique. Des artéfacts du Paléolithique moyen sont présents sur le versant en face de l'abri. Des fouilles extensives et systématiques réalisées par l'équipe d'Iringa Region Archaeological Project (IRAP) révèlent une image complexe de l'utilisation et de la réutilisation de l'abri sous roche pendant un moment important dans l'histoire de l'humanité. Des datations directes de coquilles d'Achatina et de perles en coquilles d'autruches (OES) suggèrent que l'occupation la plus ancienne excavée à Mlambalasi, associée aux sépultures humaines, parvient d'une phase terminale du Pléistocène. Ceci est exceptionnel car les sites archéologiques, en particulier contenant des corps humains et d'autres matières organiques préservées, sont rares en Afrique subtropicale entre 200,000-10,000 années avant le présent. Cet article présente les fouilles effectuées jusqu'à ce jour ainsi que l'analyse des artéfacts trouvés sur le site. L'image qui ressort est celle d'une utilisation variée et éphémère à travers les millénaires au fur et à mesure que divers groupes ont été attirés à cet endroit permanent dans le paysage.

Dietary supplement comprised of ß-carotene, vitamin C, vitamin E, and magnesium: failure to prevent music-induced temporary threshold shift.

This study examined potential prevention of music-induced temporary threshold shift (TTS) in normal-hearing participants. A dietary supplement composed of ß-carotene, vitamins C and E, and magnesium was assessed using a randomized, placebo-controlled, double-blind study design. Dosing began 3 days prior to the music exposure with the final dose consumed approximately 30-min pre-exposure. There were no group differences in post-exposure TTS or music-induced decreases in distortion product otoacoustic emission (DPOAE) amplitude. Transient tinnitus was more likely to be reported by the treatment group, but there were no group differences in perceived loudness or bothersomeness. All subjects were monitored until auditory function returned to pre-exposure levels. Taken together, this supplement had no effect on noise-induced changes in hearing. Recommendations for future clinical trials are discussed.

Surgical correction of gastro-oesophageal intussusception with bilateral incisional gastropexy in three dogs.

Three dogs presented for evaluation of acute onset tachypnoea and dyspnoea following episodes of vomiting and/or regurgitation. Thoracic radiographs were suggestive of a gastro-oesophageal intussusception in all three dogs; one dog also showed evidence of aspiration pneumonia. All three dogs underwent surgical correction with a bilateral incisional gastropexy. All dogs recovered from anaesthesia uneventfully and were discharged from the hospital 3 days after presentation. Persistent megaoesophagus was evident in all three dogs, and they are being chronically managed with a strict feeding regime and pro-motility agents.

Galaxy evolution. Black hole feedback in the luminous quasar PDS 456.

The evolution of galaxies is connected to the growth of supermassive black holes in their centers. During the quasar phase, a huge luminosity is released as matter falls onto the black hole, and radiation-driven winds can transfer most of this energy back to the host galaxy. Over five different epochs, we detected the signatures of a nearly spherical stream of highly ionized gas in the broadband x-ray spectra of the luminous quasar PDS 456. This persistent wind is expelled at relativistic speeds from the inner accretion disk, and its wide aperture suggests an effective coupling with the ambient gas. The outflow's kinetic power larger than 10(46) ergs per second is enough to provide the feedback required by models of black hole and host galaxy coevolution.

An ultraluminous X-ray source powered by an accreting neutron star.

The majority of ultraluminous X-ray sources are point sources that are spatially offset from the nuclei of nearby galaxies and whose X-ray luminosities exceed the theoretical maximum for spherical infall (the Eddington limit) onto stellar-mass black holes. Their X-ray luminosities in the 0.5-10 kiloelectronvolt energy band range from 10(39) to 10(41) ergs per second. Because higher masses imply less extreme ratios of the luminosity to the isotropic Eddington limit, theoretical models have focused on black hole rather than neutron star systems. The most challenging sources to explain are those at the luminous end of the range (more than 10(40) ergs per second), which require black hole masses of 50-100 times the solar value or significant departures from the standard thin disk accretion that powers bright Galactic X-ray binaries, or both. Here we report broadband X-ray observations of the nuclear region of the galaxy M82 that reveal pulsations with an average period of 1.37 seconds and a 2.5-day sinusoidal modulation. The pulsations result from the rotation of a magnetized neutron star, and the modulation arises from its binary orbit. The pulsed flux alone corresponds to an X-ray luminosity in the 3-30 kiloelectronvolt range of 4.9 × 10(39) ergs per second. The pulsating source is spatially coincident with a variable source that can reach an X-ray luminosity in the 0.3-10 kiloelectronvolt range of 1.8 × 10(40) ergs per second. This association implies a luminosity of about 100 times the Eddington limit for a 1.4-solar-mass object, or more than ten times brighter than any known accreting pulsar. This implies that neutron stars may not be rare in the ultraluminous X-ray population, and it challenges physical models for the accretion of matter onto magnetized compact objects.

The role of embolization in reducing the complications of cryoablation in renal cell carcinoma.

AIM: To investigate whether embolization prior to cryoablation would decrease morbidity without negative effects on tissue pathology, renal function, or recurrence. MATERIAL AND METHODS: The electronic medical records of all patients undergoing cryoablation for renal cell carcinomas were reviewed for lesion size, pre-ablative renal function, post-ablative renal function, post-ablative complications, recurrence, and quality of biopsy specimen. Comparisons were made between patients who underwent cryoablation (the Cryo-Only group) and those who underwent cryoablation after same-day coil embolization of their lesion (the Cryo-Embo group). Further comparison was made between the Cryo-Embo lesions and the subset of larger Cryo-Only lesions (≥ 3 cm), which were expected to have a higher natural complication rate. RESULTS: A total of 21 lesions in 19 patients were treated by percutaneous cryoablation (17 Cryo-Only, four Cryo-Embo). Complications were seen in 83% of the large Cryo-Only lesions (average size 3.6 cm), whereas no complication was seen amongst Cryo-Embo lesions (average size 4 cm). Embolization significantly decreased complications between size-matched lesions (p = 0.048) without impacting renal function (p = 1), biopsy quality (p = 1), or recurrence (p = 1). CONCLUSION: Performance of trans-arterial embolization prior to cryoablation of large renal cell carcinomas significantly decreases complications, such as haemorrhage, without a discernible effect on biopsy quality, renal function, or recurrence rate.

Reflection from the strong gravity regime in a lensed quasar at redshift z = 0.658.

The co-evolution of a supermassive black hole with its host galaxy through cosmic time is encoded in its spin. At z > 2, supermassive black holes are thought to grow mostly by merger-driven accretion leading to high spin. It is not known, however, whether below z ≈ 1 these black holes continue to grow by coherent accretion or in a chaotic manner, though clear differences are predicted in their spin evolution. An established method of measuring the spin of black holes is through the study of relativistic reflection features from the inner accretion disk. Owing to their greater distances from Earth, there has hitherto been no significant detection of relativistic reflection features in a moderate-redshift quasar. Here we report an analysis of archival X-ray data together with a deep observation of a gravitationally lensed quasar at z = 0.658. The emission originates within three or fewer gravitational radii from the black hole, implying a spin parameter (a measure of how fast the black hole is rotating) of a = 0.87(+0.08)(-0.15) at the 3σ confidence level and a > 0.66 at the 5σ level. The high spin found here is indicative of growth by coherent accretion for this black hole, and suggests that black-hole growth at 0.5 ≤ z ≤ 1 occurs principally by coherent rather than chaotic accretion episodes.

Assessment of nutrient supplement to reduce gentamicin-induced ototoxicity.

Gentamicin is an aminoglycoside antibiotic used to treat gram-negative bacterial infections. Treatment with this antibiotic carries the potential for adverse side effects, including ototoxicity and nephrotoxicity. Ototoxic effects are at least in part a consequence of oxidative stress, and various antioxidants have been used to attenuate gentamicin-induced hair cell death and hearing loss. Here, a combination of nutrients previously shown to reduce oxidative stress in the hair cells and attenuate hearing loss after other insults was evaluated for potential protection against gentamicin-induced ototoxicity. Guinea pigs were maintained on a nutritionally complete standard laboratory animal diet or a diet supplemented with ß-carotene, vitamins C and E, and magnesium. Three diets with iterative increases in nutrient levels were screened; the final diet selected for study use was one that produced statistically reliable increases in plasma levels of vitamins C and E and magnesium. In two separate studies, significant decreases in gentamicin-induced hearing loss at frequencies including 12 kHz and below were observed, with less benefit at the higher frequencies. Consistent with the functional protection, robust protection of both the inner and outer hair cell populations was observed, with protection largely in the upper half of the cochlea. Protection was independently assessed in two different laboratories, using two different strains of guinea pigs. Additional in vitro tests did not reveal any decrease in antimicrobial activity with nutrient additives. Currently, there are no FDA-approved treatments for the prevention of gentamicin-induced ototoxicity. The current data provide a rationale for continued investigations regarding translation to human patients.

Estimating genome-wide heterozygosity: effects of demographic history and marker type.

Heterozygosity-fitness correlations (HFCs) are often used to link individual genetic variation to differences in fitness. However, most studies examining HFCs find weak or no correlations. Here, we derive broad theoretical predictions about how many loci are needed to adequately measure genomic heterozygosity assuming different levels of identity disequilibrium (ID), a proxy for inbreeding. We then evaluate the expected ability to detect HFCs using an empirical data set of 200 microsatellites and 412 single nucleotide polymorphisms (SNPs) genotyped in two populations of bighorn sheep (Ovis canadensis), with different demographic histories. In both populations, heterozygosity was significantly correlated across marker types, although the strength of the correlation was weaker in a native population compared with one founded via translocation and later supplemented with additional individuals. Despite being bi-allelic, SNPs had similar correlations to genome-wide heterozygosity as microsatellites in both populations. For both marker types, this association became stronger and less variable as more markers were considered. Both populations had significant levels of ID; however, estimates were an order of magnitude lower in the native population. As with heterozygosity, SNPs performed similarly to microsatellites, and precision and accuracy of the estimates of ID increased as more loci were considered. Although dependent on the demographic history of the population considered, these results illustrate that genome-wide heterozygosity, and therefore HFCs, are best measured by a large number of markers, a feat now more realistically accomplished with SNPs than microsatellites.

Consistent divergence times and allele sharing measured from cross-species application of SNP chips developed for three domestic species.

Recent advances in technology facilitated development of large sets of genetic markers for many taxa, though most often model or domestic organisms. Cross-species application of genomic technologies may allow for rapid marker discovery in wild relatives of taxa with well-developed resources. We investigated returns from cross-species application of three commercially available SNP chips (the OvineSNP50, BovineSNP50 and EquineSNP50 BeadChips) as a function of divergence time between the domestic source species and wild target species. Across all three chips, we observed a consistent linear decrease in call rate (~1.5% per million years), while retention of polymorphisms showed an exponential decay. These results will allow researchers to predict the expected amplification rate and polymorphism of cross-species application for their taxa of interest, as well as provide a resource for estimating divergence times.

A 200-second quasi-periodicity after the tidal disruption of a star by a dormant black hole.

Supermassive black holes (SMBHs; mass is greater than or approximately 10(5) times that of the Sun) are known to exist at the center of most galaxies with sufficient stellar mass. In the local universe, it is possible to infer their properties from the surrounding stars or gas. However, at high redshifts we require active, continuous accretion to infer the presence of the SMBHs, which often comes in the form of long-term accretion in active galactic nuclei. SMBHs can also capture and tidally disrupt stars orbiting nearby, resulting in bright flares from otherwise quiescent black holes. Here, we report on a ~200-second x-ray quasi-periodicity around a previously dormant SMBH located in the center of a galaxy at redshift z = 0.3534. This result may open the possibility of probing general relativity beyond our local universe.

Quantitative coronary arterial stenosis assessment by multidetector CT and invasive coronary angiography for identifying patients with myocardial perfusion abnormalities.

BACKGROUND: Semi-quantitative stenosis assessment by coronary CT angiography only modestly predicts stress-induced myocardial perfusion abnormalities. The performance of quantitative CT angiography (QCTA) for identifying patients with myocardial perfusion defects remains unclear. METHODS: CorE-64 is a multicenter, international study to assess the accuracy of 64-slice QCTA for detecting ≥50% coronary arterial stenoses by quantitative coronary angiography (QCA). Patients referred for cardiac catheterization with suspected or known coronary artery disease were enrolled. Area under the receiver-operating-characteristic curve (AUC) was used to evaluate the diagnostic accuracy of the most severe coronary artery stenosis in a subset of 63 patients assessed by QCTA and QCA for detecting myocardial perfusion abnormalities on exercise or pharmacologic stress SPECT. RESULTS: Diagnostic accuracy of QCTA for identifying patients with myocardial perfusion abnormalities by SPECT revealed an AUC of 0.71, compared to 0.72 by QCA (P = .75). AUC did not improve after excluding studies with fixed myocardial perfusion abnormalities and total coronary arterial occlusions. Optimal stenosis threshold for QCTA was 43% yielding a sensitivity of 0.81 and specificity of 0.50, respectively, compared to 0.75 and 0.69 by QCA at a threshold of 59%. Sensitivity and specificity of QCTA to identify patients with both obstructive lesions and myocardial perfusion defects were 0.94 and 0.77, respectively. CONCLUSIONS: Coronary artery stenosis assessment by QCTA or QCA only modestly predicts the presence and the absence of myocardial perfusion abnormalities by SPECT. Confounding variables affecting the relationship between coronary anatomy and myocardial perfusion likely account for some of the observed discrepancies between coronary angiography and SPECT results.